"Version 4.6 of GCC was released over the weekend with a multitude of improvements and version 2.9 of the Low-Level Virtual Machine is due out in early April with its share of improvements. How though do these two leading open-source compilers compare? In this article we are providing benchmarks of GCC 4.5.2, GCC 4.6.0, DragonEgg with LLVM 2.9, and Clang with LLVM 2.9 across five distinct AMD/Intel systems to see how the compiler performance compares."

What on earth are you talking about? They are testing compilers: that's feed them some source code and inspect the machine code on a specific aspect and here, they've chosen to inspect either the speed of the compiled code or the time taken by each compiler to compile.

What do you expect as "data sets"? The source code of each program that compiled? Or for instance, the data used as input to the compiled program? like the video used for the x264 encoding? or the files used for the 7-zip compression?